Fuel control in internal-combustion engines



July 26, 1927.

` H. JUNKERS y FUEL CONTROL 1N INTERNAL coMBUsTIoN ENGINES Filed NOV.17. 1921 .Il en. wlhlllll Patented July Z6, 1.927.

UNITED sTATEs y A 1,536,998 PATENT OFFICE.

HUGO JUNxnas, or Dessau, annum.

FUEL'Y CQN'LBOL4 IN INTERNAL-COMBUSTION ENGINES.

Applieationilled November 17, 1921, Serial No. 515,987, and in Germany June 1, 1921.

My invention relates to internal combustion engines-and more especially toy the delivrybf fuel in suchengines.

@In linternal combustion engines in which liqgid fuel is injected into a strongly conifpressed charge of airnear the inner dead Acenter and -ignited by the heat of compression, it is known to inject the fuel positively, that is, without the aid of atomizing air. v

If Ait be desired to dispense with a`sepa rate controlled injection valve at the pointpf injection in the working cylinder of such v engine, the be inning and the end of the injection peri must be determined exclusively by the fuel pump. By dispensing with such control valve, the design of the engine is greatly simplilied and moreover the dangers are obviated which-are caused by the sticking of thevalve, viz. excessive and inadmissible increase of pressure in the working cylinder in consequence of too early in-` jection of fuel. 2

My "nvention relates to a method of so controlling the fuel pump that the process of injection is controlled exclusively by the fuel p'ump. To this end, I so'control the pump that the beginning of delivery in relation to the crank circle or the stroke of the working piston is approximatelyconstant for all loads while the end of the delivery is determined by the operation of an adjustable actuating member of `the pump or its control. 'As compared to the injection by compressed air, the advantage is .hereby achieved that the injection is positively efected at all numbers-of revolutions within a predetermined angular movement of the crank, so that a perfect control of the process of combustion is possible under` all con- Y ditions of operation andno dangerous increase of pressure atlow speed can occur.

- AMy invention may be carriedout in various ways.. I prefer varying the quantity delivered or, in other words, the charge by aid of a cam whose angular positioncan be adjusted. Itmay be 'turned concentrically to its shaft, but, in this case, special meansare required for fixing the constant beginning ofdelivery, such as, for instance, a separate I- control of the suction valve or a separate u l about a point eccentric to the axis 'of CIthe auxiliary cam whose motion determines thel beginning ofthe delivery stroke proper.

'edJaS t0 vHowever the cam for .actuatin -tlie um i adjpuste `may also be so arra shaft', the constant beginning of delivery belifting surface o the cam the form of part of acircle surrounding this centre. I further prefer provided' means by which the pump piston is rapidly withdrawn for a short distance immediately after having attained the end ofits deliverystroke, for example by an abruptly descending surface on the cam immediately following its highest point, lor by means of equivalent means'in the system, of controlling levers. In this way an'afterdrippin of the nozzle, afterv injection has been e ected, is avoided.

In the drawings axed to this specification and forming part thereof, vseveral embodiments of my invention are illustrated diagrammatically by way of example. In the drawings Fig. 1 is a partial longitudinal section of the working cylinder, the fuel pump and the actuating gear,

Fig. 2 is a like view of a modied form, Fig. 3 is a similar -view of a fuel pum and an adjustable cam having an eccentric pivot,

such a cam.

Referring to Fig.. 1, the piston 1 of the pump is actuated by a ,cam 3 adaptedto be adjusted circumferentially o'n a shaft 2 in such amanner that the stroke of piston 1a will be constant, these strokes however, be-

ginningand ending at various points of the crankcircle accordin to the positions of F'g. 4 is a` section of a modified form of' the cam. The cam ma be adjusted by hand or by aid of a governor. The beginning of the delivery is determined by the closing of the suction valve 4 of the pump, while its end 395 nis determined by the end of the piston stroke. In order to always close the valve 4 at the same point of the'crank circle, it is posispring 4* and opens outwards, thus also forming a safety valve for the pump.

This 'arrangement may be modified causii'i the governor to ad'ustnot thej'cam 3 but e eccentric 6. In this case the pump with its uniform motion will determine the fbi.

constant beginning and the variabl moment of op1 .of t e delivery stroke.

no fuel is as ing'surface o ening of valve 4 will determine the end The valve 4 may then be kept open so long that it not only operates as a non-return valve in the sense referred to, but also as a suction valve for Vthe pump. I may, however,.provide a special suction device, either tion port;

In the modification illustrated in Fig. 2, the beginning and the end of the delivery are determined by two cams 11 and 12, which both act on the pump piston 1, thus rendering controlled valves atthe pump superflu-A ous. Cams 11 and 12 are located on parallel shafts 15 and 16 which are coupled by gears 13 and 14. The shafts revolve with equal a valve or a sucspeed but in opposite directions as indicated by the arrows. The cams cooperate with rollers 17 and 18 which are connected with oneanother and with the piston 1 by means of a lbalance lever 19. Cam 11 is fixed on shaft .15, whereas cam 12 may be adjusted as circumferential] with regard to shaft 16 orgear 14 by'han or by aid of a governor.

This pump operates as follows: first, the roller 18 is lifted by cam 12, yso that the piston 1 is raised to near the inlet port 20 which it controls. During this stroke of the piston yet delivered. When the liftcam 11 engages roller 17, the piston 1is raised further, so as to close port 20. At this moment the delivery begins and is' continued until. the roller 18 .passes the rear surface of cam 12 and piston 1 returns in order to start for the suction stroke. As the cams revolve further, the roller 17 also passes over the rear face of cam 11. In this period the piston 1 performs an ineffective stroke. -Owing to the cam 11 being rigidly fixed on shaft 15 the inlet port 20 is closed and delivery-begins always at the same position ofthe crank ofv the working piston. The length of the 'effective pumV piston stroke Vdepends 'upon whether, whi e roller 17 is being lifted by cam 11, roller 18 still runs on the base circle of cam 12 or is already about' to pass over the rear face of the cam. While in the former case-the maximum quantity is delivered, it is small in the latter case and nil when roller 18 has already reached the-base circle of cam 12,

- while-roll r 17 is being lifted by cam 11.

Further sim liication is effected' according to Fig. 3, by disposing the pivot 21, of ca1`n22 eccentrically to the axis 23 of thel cam shaft. In this case the delivery of the pump may be adjusted by means of a single cam without providing separate means for maintaining t by forming theA lifting surface 24 of the cam accordin to a circle drawn around its pivot 21. The ifting surface-of cam 22 then Intersects the `1nain cam 25 in the same point26 at-all positions of cam 22,` so that the piston e beginning of delivery con. stant. This is achieved in a simple manner tially to surface 24 at 26. According to the positionA of cam 22, its radial projection Abeyond the main cam 25 and with it the pump stroke vary. Immediately adjoining the highest point of face 24, there extends an abrupt portion 27, of the rearsurface which effects a rapid backward movement of the pump piston immediately after it has performed its delivery stroke. This prevents drops of fuel from emerging from the nozzle after the injection. V

The device illustrated in Fig. 3 is further improved by forming the cam 22 as a closed ring surrounding the shaft 31 as illustrated in Fig. 4. This cam has a lifting surface 24, concentric with its pivot 21 and a base circle 32 replacing the base circle 25 in Fig. A13. On the shaft 31 is fixed a spider 33 carrying a pair of centrifugal masses 34 acted upon by springs 35 and coupled by means of rods 36, 37 pivoted to the lever 38 which is connected with the cam 32 whereby, when the position of the masses 34 is changed, the cam will rock about the pivot 21. Owing to the approximately circular form of the surface 32 no undue accelerations and no excessive inefl'ective strokes will occur.

The cams are preferably adjusted in all cases by means of a shaft governor lon the cam shaft. Instead of cams eccentrics or cranks may be provided, which are connected with the governor in a manner similar to that of adjustable cam disks and eccentrics.

The means disclosed in Figs. 2 to 4 for actuating the pump piston may also be used for actuating a valve such as 4 in Fig. 1. In this case the pump piston will be imparted a permanently constant stroke by means of an unvariable actuating member and the entire control of the pump includ-^ ing the beginning and the end fof delivery, is determined exclusively by the closing and opening ofl the valve. This arrangement renders necessary one actuating part more than the others, but it involves the advantage vthat the cam surfaces which owing to the high fuel pressure are subject to heavy wear, are combined at the valve and can easilybe exchanged.

1. Means for 'regulating the delivery of fuel in internal combustion en ing a fuel pump cylinder an piston, controlling means in said pump for causing the .end of the effective strokes to coincide with the vend of the pump stroke, an engine crank. shaft, a rotating member driven by said crank shaft for driving said pump piston and shiftable in its plane of movement, a regulating device, means connecting said es comprismember and regulating device for shifting said member in the plane of its movement so as to -drive said pump piston with strokes of varying ends with regard to the engine crank circle, and means for keeping the commencement of delivery of said pump constantwith respect to the engine crank circle.

2. In a device of the kind described in combination, a fuel pump cylinder and piston, an engine crank shaft, a controlled admission means connected with said cylinder, means for closing said admission means always at the same point of the crank circle and means for moving said piston adapted to be adjusted so as to shift the end of the delivery stroke of said piston.

3. In adevice of the kind described in combination, a fuel pump cylinder and piston, an engine crank shaft and a cam capable of adjustment in its plane of rotation for varying the e'ective stroke of said piston while causing the delivery of the fuel vto always begin at the same point of the crank circle.

4. In a device of the kind described in combination, a fuel pump cylinder and piston, an engine crank shaft, a controlled admission means connected with said cylinder, means for closing said admission means always atthe same 'point of the crank circle and a cam capable of adjustment in its plane of rotation for moving said piston.

5. In adevice of the kind described in combination, a fuel pump cylinder and piston, an engine crank shaft, a cam capable of adjustment in its plane of rotation for varying the effective stroke of said piston while causing the delivery of the fuel to always begin at the same point of the crank circle, and a governor for adjusting said cam.

6. In a device of the ,kind described in combination, a fuel ipump cylinder and piston, an engine crank shaft, a controlled admission means connected with said cylinder, means for closing said admission means always at the same point of the crank circle, a cam capable of adjustment in its plane of rotation for moving said piston and a governor for adjusting said cam.

7. Ina device of the kind'described in combination, a fuel pump cylinder and piston, an engine crank shaft and means for varying the effective stroke of said piston while causingthe delivery of the fuel to always begin at the same point of the crank circle, s aid means comprising a cam adapted to turn about an eccentric pivot 'and whose lifting surface -has the form of part of a circle concentric to said pivot.

8. In a device of the kind described in combination, a fuel pump cylinder and piston, an engine crank shaft and means for varying the effective stroke of said piston while causing the delivery of the fuel to always begin at the same point of the crank circle, said means comprising a cam shaft and an annular cam surrounding said shaft and adapted to turn about an eccentric pivot outside said shaft, the lifting surface of said cam having the form of part of a circle concentric to said pivot.

9. In a device of the kind described in combination, a fuel pump cylinder and pist0n, an engine crank shaft, means for varying the effective stroke of said piston while causing the delivery of the fuel to always begin at the same point of the crank circley and means for a quick return of said pump piston at the end of its delivery stroke.

In testimony whereof I aiiix my signature.

HUGO JU NKERS. 

